1. Field of the Invention
The field of the invention relates to attachments for portable power tools. More particularly, the field of the present invention relates to attachments for power tools of the type which have rotary-hammer mechanisms and selector means for alternately establishing rotation (with or without combined hammering) and hammering-only modes of operation. Such power tools use a drill bit and are particularly suited for drilling holes in concrete, for example.
2. The Prior Art
Power tools of the type here under consideration are powered by either an electric or pneumatic motor and include so-called rotary-hammer mechanisms. In certain of these tools, one mechanism is capable of imparting combined rotation and axial impact blows to a tool element, such as a drill bit. These tools include a manually operable selector lever for engaging and disengaging the rotation imparting mechanism thereby to provide a hammer-only mode of operation. Representative power tools of this type are disclosed in U.S. Pat. Nos. 3,837,409 and 3,845,826, both assigned to the assignee of the present application.
One well known use of these power tools is for installation of concrete anchors. When it is desired to install such an anchor, the power tool is operated in the combined rotation and hammering mode of operation thereby rapidly to drill a hole in a concrete structure. Thereafter, the drill bit is removed and replaced by an attachment particularly adapted for driving the slugs forming part of these concrete anchors. After this attachment is secured to the tool, the selector lever is actuated such that the power tool will impart hammer-only blows to the attachment thereby to hammer the anchor slug in place. Thus, when installing a number of concrete anchors, it is necessary repeatedly to detach and attach both the drill bit and the separate anchor installing tool. This is a rather time consuming task and requires the use of two completely separate tool elements.
Operators of these power tools often find it necessary to perform chiseling work during the course of drilling in a concrete structure, for example. In carrying out this type of work, it is necessary for the operator to make frequent changes to the tool elements. That is to say, he must frequently remove the drill bit, replace it by a chiseling tool element, and then later reinsert the drill bit. This is a rather time consuming operation and requires again two separate and independent tool elements.